Understanding Prostate Cancer Gleason Scores

This page is for anyone reading a prostate biopsy report. It explains Gleason scores and Grade Groups, what they change about treatment options, and what they cannot tell you.

A Gleason score describes how abnormal prostate cancer cells look under a microscope. A pathologist (a doctor who studies tissue) looks at the tissue from your biopsy. They grade the pattern of the cells, not just how many there are. This tells your care team how the cancer is likely to behave.

The scale runs from pattern 3 to pattern 5. Pattern 3 looks the most like normal prostate tissue. Pattern 4 looks more abnormal. Pattern 5 looks the most abnormal, with cells that have lost their normal structure almost completely.

Prostate tumors are rarely made of just one pattern. So pathologists grade the two most common patterns they see. The primary pattern takes up the most space in the sample. The secondary pattern is the next most common.

These two numbers are added together. A tumor that is mostly pattern 3, with some pattern 4, is written as Gleason 3+4=7. A tumor that is mostly pattern 4, with some pattern 3, is written as Gleason 4+3=7. Both add up to 7. But they are not the same cancer. More pattern 4 means a more aggressive cancer, even though the total score matches. This is why your report lists both numbers, not just the sum.

Gleason scores usually range from 6 to 10.

Because two different combinations can both add up to 7, doctors created a second system called Grade Groups. It sorts every Gleason combination into five simpler categories, numbered 1 through 5.

• Grade Group 1: Gleason 6 or lower. This is the least aggressive category.
• Grade Group 2: Gleason 3+4=7, where pattern 3 dominates.
• Grade Group 3: Gleason 4+3=7, where pattern 4 dominates.
• Grade Group 4: Gleason 8.
• Grade Group 5: Gleason 9 or 10. This is the most aggressive category.

Higher Grade Groups are linked with cancer that is more likely to grow and spread quickly. Your report may show both the Gleason score and the Grade Group together. They describe the same finding in two different ways.

Grade Group is one of the main factors used to plan prostate cancer treatment. It is weighed alongside your PSA level and the stage of the cancer. Grade Group 1 cancer, especially if it is small and PSA is low, is often eligible for active surveillance. That means monitoring the cancer closely with PSA tests, exams, and repeat biopsies, instead of treating it right away.

Higher Grade Groups usually point toward more immediate treatment, such as surgery or radiation, sometimes combined with hormone therapy. The exact recommendation still depends on your PSA, your imaging results, your age, and your overall health.

A Grade Group describes the cells seen in your biopsy sample, not the whole prostate. A biopsy only samples part of the gland. The true highest-grade area could occasionally be missed. Grade also does not equal stage. Stage describes the size of the tumor and whether it has spread beyond the prostate. A Grade Group 4 cancer still confined to the prostate is a different situation from the same grade found alongside spread to lymph nodes or bone.

• What is my Gleason score, written as two numbers, and what is my Grade Group?
• Is active surveillance an option for me, or does my grade point toward treatment now?
• How do my PSA level and imaging results fit with this grade?
• Could a repeat biopsy or more imaging change this picture?

Gleason grading involves real judgment, and pattern 3 versus pattern 4 can be a close call in some samples. Active surveillance decisions often hinge on this exact difference. So it is reasonable to ask whether a second pathologist can review your slides, especially if the case is borderline. If you are considering active surveillance, it is reasonable to ask whether your slides have been reviewed by a genitourinary pathology specialist.

• National Cancer Institute — PDQ Prostate Cancer Treatment (Patient Version)
• National Cancer Institute — Tumor Grade Fact Sheet